Regensburg 2013 – scientific programme

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DS: Fachverband Dünne Schichten

DS 10: Organic Electronics and Photovoltaics I (jointly with CPP, HL, O)

DS 10.6: Talk

Monday, March 11, 2013, 18:30–18:45, H32

Effective Charge Carrier Lifetimes in Organic Solar Cells Prepared by Coevaporation of C60 and CuPc in different mixtures and geometries — •André Dragässer and Derck Schlettwein — Institute of Applied Physics, Justus-Liebig-University Giessen, Giessen, Germany

Evaporated organic solar cells can lead to efficiencies of technical relevance if the interface of donor and acceptor molecules is optimized for the interplay of exciton dissociation, charge transport and recombination. The effective lifetime of the charge separated state is of central relevance. Intensity- modulated photovoltage spectroscopy with parallel impedance spectroscopy is a suitable method of analysis. Organic solar cells consisting of the well-established semiconductor materials CuPc and C60 were prepared by physical vapor deposition on an ITO substrate, modified with PEDOT:PSS. The cells were completed by a back contact of BCP as a buffer and aluminum. Cell architectures of planar junctions, bulk heterojunctions or planar-mixed heterojunctions were studied for different film thickness of the components. IV-measurements in the dark and under varied illumination intensities provided basic device characteristics. Detailed measurements of the short-circuit photocurrent and the open-circuit photovoltage under static or intensity-modulated illumination with different wavelength were performed to determine the average charge carrier lifetime in the devices which was related to the respective charge carrier density obtained by impedance spectroscopy. Recombination reactions and, in particular, the influence of trap states will be discussed.